1. Field of the Invention
The present invention relates to a digital still camera which analyzes a feature of an image.
2. Related Background Art
In case of intending to satisfactorily output an output image based on image data by a printer and a display, it is necessary for each of plural objects constituting the output image to perform color processes such as a color correction process, a color conversion process, a binarization process and the like according to a kind of object. Generally, in case of printing or displaying an image formed based on a computer application, a device driver or a device performs rasterizing of a drawing command group issued based on the computer application to generate bitmap image data for a whole page, thereby performing the printing or the displaying based on the generated bitmap image data.
In recent years, according to a system or an application, a source profile is designated in regard to each of the objects constituting the image, whereby the device driver can obtain a higher-quality output by using the contents of the designated source profile. For example, in a case where a scanner-input image is affixed to an electronic document, a color profile which describes a device characteristic of the scanner is designated in a drawing instruction for the scanner input image. Further, in a case where color calibration or the like is performed on the display, a color profile which describes characteristics of a monitor used by an editor to edit the original image is designated to faithfully reproduce the color viewed by the editor. Incidentally, the above color profile may be, e.g., an ICC (International Color Consortium) profile. Besides, ICM™ of Windows™ available by Microsoft, ColorSync™ available by Apple Computer, and the like are known as systems which can use the above profile.
In addition to such a delicate color matching processing system, in a photographic image, even if the quality of an original image itself is inferior, there are some techniques to obtain a beautiful and high-quality output from the inferior original image. For example, if exposure of an image shot by a digital still camera which has been recently in widespread use is inappropriate, a user has to perform an image correction process such as a nonlinear color balance process or the like by using an image retouch application to improve the inappropriately exposed image. However, in such a case, if a user not having high knowledge and experience tries to perform the setting for the appropriate correction process, he has to repeat it by trial and error, whereby it takes an excessive time.
Thus, there is a technique to automatize such an image correction by using the method disclosed in Japanese Patent Application Laid-Open No. 2000-13625 or the like, and the technique is applied also to an image recording apparatus. In Japanese Patent Application Laid-Open No. 2000-13625, a histogram concerning brightness is created based on pixel data of an original image, the pixel data accumulated from a predetermined pixel value and corresponding to a predetermined frequency is detected, highlight and shadow points are obtained based on the detected pixel data, and an image correction process to correct color fogging of the entire image is performed based on the obtained highlight and shadow points, thereby achieving a high-quality image with a low processing load.
On one hand, according to popularization of a digital still camera, a demand for image output from a so-called photo-direct (PD) printer or the like is increasing. Here, it should be noted that, in the printing of the image by using the PD printer, the data of the digital still camera is first stored in a recording medium such as a CompactFlash™ card (simply called a CF card hereinafter) or the like, the CF card is then inserted into a card slot provided on the body of the printer, the data stored in the CF card is thus read and printed directly by the printer without any host computer. Moreover, a PD printer system is being popularized. Here, it should be noted that, in the printing of the image by using the PD printer system, the data of the digital still camera is directly transferred to the PD printer via an interface such as a USB (universal serial bus) or the like (i.e., not using any recording medium), the received data is then converted into data for data recording on the printer side, and the data recording is actually performed by the printer on the basis of the converted data.
The above PD printer includes an image processing function called a controller unit. Thus, various processes such as image rendering, rasterizing, color conversion, quantization, print control command generation and the like which are ordinarily performed on the host computer side are all performed on the controller unit side, and the processed data is then transferred from the controller unit to an engine unit. Then, the engine unit analyzes a print control command and print data in the transferred data, and thus performs mechanical control such as paper feeding control, carriage movement control and the like necessary to record the image on a recording paper. Moreover, the engine unit performs control to apply a driving pulse to a recording head, control to transmit the data to the recording head, and the like. Here, it should be noted that the above control in the engine unit is the same as the control to be performed in a conventional case where the data from a host PC is received by the engine unit.
Moreover, in recent years, a technique has been adopted such that printer control information for a specific printer is filed in advance on the digital still camera side together with image data, the information is then transferred and obtained on the specific printer side, and the obtained information is corrected on the printer side when the image data is actually recorded. Here, it should be noted that the printer control information for the specific printer concerns designation of print parameters (an amount of correction in regard to a print density, etc.), print control, and the like.
However, in a case where the above technique for appropriately correcting the image transferred from the digital camera or the like is achieved in the PD printer, such problems as follows are recognized.
That is, in a case where an image stored in a recording medium such as the CF card or the like is corrected and then printed, the number of accesses to the CF card increases, and print speed substantially decreases.
More specifically, a user accesses the CF card to read the stored data file for an ordinary print data generation process. In addition, the user has to access the CF card once in advance to read and analyze the image file in order to create a histogram necessary for the image correction. Although it is possible to perform both the advance access for the image correction and the access for the ordinary color process in a lump, a large-capacity memory capable of expanding and holding all the read image data in this case is necessary in the body of the PD printer, whereby the cost greatly increases. Moreover, as the number of recording pixels increases every year due to development in the image quality of the digital still camera, the cost increase in regard to the memory becomes large.
Incidentally, an image shot by the digital still camera is generally stored often in the form of a compressed file according to a JPEG (Joint Photographic Experts Group) standard or the like (hereinafter such a compressed image is simply called a JPEG image). In this case, since the content of the JPEG image itself cannot be seen until the data is decompressed, decompression of the JPEG image data as well as the file access is necessary to create the histogram. Thus, a data processing amount further increases, whereby print speed decreases.
Moreover, in a case of laying out and recording plural images on one recording paper, since the number of image files to be analyzed further increases, the number of times the file is accessed and the JPEG image data is decompressed also increases. Thus, the process load further increases as the number of files increases, whereby print speed decreases.
Moreover, in a case where image data previously stored in the storage medium of the digital still camera is then read directly from the body of the PD printer and then printed, as well as the above case of reading the data from the recording medium, the number of times a file is accessed and the number of times JPEG image data is decompressed increases, whereby the process load increases. Thus, print speed decreases.
Moreover, in the above technique when the printer control information concerning the designation of print parameters (the amount of correction in regard to the print density, etc.), the print control, and the like are filed in advance on the digital still camera side together with the image data, it is impossible to avoid that this information is provided in consideration of the specific characteristics of the recording device which should perform the printing. Thus, when an unexpected recording device is used, the above information becomes meaningless, and thus it is inappropriate for general use.